What bird is that? The grim task of identifying seabirds killed by the M.V. Rena oil spill

What bird is that? The grim task of identifying seabirds killed by the M.V. Rena oil spill

Te Papa bird staff are providing expert assistance to Maritime New Zealand and Massey University veterinary staff in the form of identifying birds affected by the oil spill. Three current and one former staff member have been a ‘tag team’ since 12 October, identifying the hundreds of corpses recovered by the teams patrolling the beaches, plus any picked up at sea. There are many seabird species potentially present in the Bay of Plenty at this time of year. Making sure that each bird is correctly identified is essential for understanding the impacts of the spill. This information will be crucial if there is any potential for environmental mitigation after the clean-up is complete.

Identifying heavily oiled birds is a challenge, especially when the oil is thick and tar-like. Not only are all plumage markings, bill and leg colour concealed, but it can even be difficult to determine the shape of the bill, which is otherwise diagnostic for many species. For some birds it is necessary to use body structure – the relative length of the tail separates the similarly-sized Buller’s and sooty shearwaters. For others, knowing the one crucial identification character to check (e.g. leg colour) to separate species pairs means that a bird can be identified more rapidly.

The work is dirty, smelly, frustrating, and deeply saddening for anyone who knows the beauty of these birds in their prime. Over 20 species of seabird have been identified dead and coated with oil so far, ranging in size from tiny white-faced storm petrels to an enormous wandering albatross. The three main species affected (common diving petrel, fluttering shearwater and Buller’s shearwater) are not threatened species, but their populations will take decades to recover from a mortality event of this scale. All lay a maximum of one egg per pair each year, and the two shearwaters do not start to breed until they are about 5 years old.